LATE PLEISTOCENE SEA-LEVEL CHANGE IN THE BAHAMAS FROM MASS-SPECTROMETRIC U-SERIES DATING OF SUBMERGED SPELEOTHEM

The dating of sea level events by a method independent of orbital tuni ng techniques and the marine foraminiferal isotopic record provides a test of both the dating of the marine record and the strength and natu re of the relationship between climatic change, sea level change and M ilankovitch cycles. Dating of fossil corals and submerged speleothem p rovides such independent information. Results of thermal ionization ma ss spectrometric U-series dating on layers of flowstone speleothem fro m Lucayan Caverns, Grand Bahama Island indicate that multiple sea leve l events have passed through a depth of -10 to -15 m below modern sea level during the last 300,000 years. These data are used to constrain the magnitude and timing of sea-level fluctuations during the late Ple istocene. The new sea level curve constructed from these data correlat es closely with the marine isotopic record: sea level peaks occurred a t around 233, 215, 125 and 100 ka BP. There is no evidence at the dept h from which this speleothem was retrieved of any high sea stands at 1 95 or 80 ka corresponding to the foraminiferal 7a and 5a oxygen isotop e peaks. There is also no evidence of a double rise around the 125 ka (5e) peak, although such an oscillation could have occurred above -10 m leaving no record in the Lucayan Caverns speleothem.